The present invention relates to a solar cell module having a solar cell and a power converter, and a power generator using this solar cell module.
Recently, a large number of solar power generating systems are installed to solve environmental problems and the like. In these systems, electric power generated by a solar cell (to be also referred to as a xe2x80x9cphotovoltaic elementxe2x80x9d hereinafter) is converted by a power converter, and this power is supplied to a load in a house and/or a commercial power system (to be referred to as a xe2x80x9csystemxe2x80x9d hereinafter).
In addition, a solar cell module (photovoltaic element module) has attracted attention as a small- or medium-scale solar power generating system or as an emergency power supply. In this solar cell module, a small power converter (to be referred to as a xe2x80x9cpower converterxe2x80x9d hereinafter), called an Module Integrated Converter (MIC), for converting electric power generated by a solar cell (photovoltaic element) is attached to the surface (to be referred to as a xe2x80x9crear surfacexe2x80x9d hereinafter) opposite to the solar cell light-receiving surface (to be referred to as a xe2x80x9clight-receiving surfacexe2x80x9d hereinafter).
Unfortunately, this solar cell module has the following problem. That is, the temperature of the light-receiving surface of the solar cell module rises, and the heat is conducted to the rear surface of the solar cell module. This heat conduction raises not only the temperature of the rear surface on which the power converter is usually mounted, but also the temperature of a power conversion-circuit installed in this power converter.
That is, when the heat conduction from the light-receiving surface of the solar cell module raises the temperature of the power converter, the performance lowers and the power conversion efficiency worsens. In some cases, the power converter may be damaged.
As described above, if insulation of the heat conducted from the solar cell module (photovoltaic element module) to the power converter and radiation of the heat from the power converter are insufficient, the power conversion efficiency worsens, and the power converter may be damaged, or the life of the power converter may shorten even if no immediate damage occurs. To solve this heat problem, Japanese Patent Laid-Open No. 9-271179 discloses an arrangement in which a power converter is mounted in a gap formed in the rear surface of a solar cell module.
When, however, this solar cell module is to be integrated with a building material such as a roofing material, this rear-surface space is very narrow, so the power converter must also be very small. Accordingly, when the power converter is mounted in a gap as in the above disclosure, a large space is necessary, and this interferes with downsizing of the solar cell module. Also, the strength of a structure having a gap as in the above disclosure is low from a viewpoint of mechanics.
The present invention has been made to solve the problems of the prior art described above, and has as its object to provide a solar cell module (photovoltaic element module) in which a solar cell module (photovoltaic element module) main body containing a solar cell (photovoltaic element) is integrated with a power converter for converting output electric power from the solar cell, and which is suited to downsizing and capable of improving the efficiency and reliability of the power converter.
To achieve the above object, a solar cell module of an embodiment according to the present invention has the following arrangement. That is, a power converter comprises a power conversion circuit for converting an output from a photovoltaic element and outputting the converted output, and a protective case containing the power conversion circuit, characterized in that the protective case comprises a first portion for fixing the protective case to a predetermined portion of a photovoltaic element module having the photovoltaic element, and a second portion for fixing the power conversion circuit, and the first and second portions are made of materials different in thermal conductivity.
For example, the power converter is characterized in that the thermal conductivity of the material of the first portion is smaller than that of the material of the second portion.
For example, the power converter is characterized in that the material of the first portion is a plastic material containing one member selected from the group consisting of polycarbonate, polyamide, polyacetal, modified PPO (PPE), polyester, polyallylate, unsaturated polyester, a phenolic resin, an epoxy resin, polybutyleneterephthalate, nylon, polypropylene, polyvinyl chloride, and an ABS resin.
For example, the power converter is characterized in that the material of the second portion contains one member selected from the group consisting of an aluminum plate, stainless steel plate, zinc-plated steel plate, galvalume steel plate, titanium steel plate, and stainless steel plate.
For example, the power converter is characterized in that the material of the second portion is a resin mixed with a thermally conductive material.
For example, the power converter is characterized in that the thermally conductive material contains at least one of a metal powder, metal oxide, metal fibers, metal-coated glass beads, and synthetic fibers.
For example, the power converter is characterized in that a metal forming the thermally conductive material contains at least one of Al, Cu, Ni, ZnO, SnO2, Ag, and stainless steel.
For example, the power converter is characterized in that the thermally conductive material contains at least one of carbon black, carbon fibers, and graphite.
For example, the power converter is characterized in that the material of the first portion is a plastic material containing one member selected from the group consisting of polycarbonate, polyamide, polyacetal, modified PPO (PPE), polyester, polyallylate, unsaturated polyester, a phenolic resin, an epoxy resin, polybutyleneterephthalate, nylon, polypropyrene, polyvinyl chloride, and an ABS resin.
For example, the power converter is characterized in that the power conversion circuit is fixed in contact with a surface of the second portion.
For example, the power converter is characterized in that the power conversion circuit is fixed away from the second portion.
For example, the power converter is characterized in that the power conversion circuit is fixed to the second portion by using fixing means.
For example, the power converter is characterized in that the fixing means is mechanical fixation using a screw or fixation using an adhesive or filler.
For example, the power converter is characterized in that an adhesive or filler is packed between the protective case and the power conversion circuit.
For example, the power converter is characterized in that the power converter is an inverter which converts DC power into AC power.
For example, the power converter is characterized in that the power conversion circuit is mounted on a substrate having a metal core.
For example, the power converter is characterized in that the power converter is a DC/DC converter which converts DC power into another DC power having a different voltage.
For example, the power converter is characterized in that the photovoltaic element contains one member selected from the group consisting of a silicon semiconductor, compound semiconductor, single-crystal silicon, polysilicon, amorphous silicon, and thin-film polysilicon.
For example, the power converter is characterized in that the photovoltaic element is filled with a transparent insulating member and contained in a main body of the photovoltaic element module.
For example, the power converter is characterized in that the insulating member is rendered transparent by the use of one member selected from the group consisting of an ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and polyvinyl butyral resin.
To achieve the above object, a photovoltaic element module of an embodiment according to the present invention has the following arrangement. That is, a photovoltaic element module comprises a power converter comprising a power conversion circuit for converting an output from a photovoltaic element and outputting the converted output, and a protective case containing the power conversion circuit, and a photovoltaic element module main body having the photovoltaic element, characterized in that the protective case comprises a first portion for fixing the protective case to a predetermined portion of the photovoltaic element module having the photovoltaic element, and a second portion for fixing the power conversion circuit, and the first and second portions are made of materials different in thermal conductivity.
To achieve the above object, a power generator of an embodiment according to the present invention has the following arrangement. That is, a power generator uses a photovoltaic element module comprising a power converter comprising a power conversion circuit for converting an output from a photovoltaic element and outputting the converted output, and a protective case containing the power conversion circuit, and a photovoltaic element module main body having the photovoltaic element, characterized in that the protective case comprises a first portion for fixing the protective case to a predetermined portion of the photovoltaic element module having the photovoltaic element, and a second portion for fixing the power conversion circuit, and the first and second portions are made of materials different in thermal conductivity.
For example, the power generator is characterized in that the power generator comprises a plurality of photovoltaic element module main bodies, and the plurality of photovoltaic element module main bodies are connected to the power converter.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.